1. Field of the Invention
The present invention relates to a multiway valve with a piston slide valve and at least five control chambers.
2. Discussion of the Background
A multiway valve is described, for example, in DE-PS 33 09 065. In this known case the ducts in the piston slide valve are formed by blind holes, which, on the one hand, are connected by radial bores in the piston slide valve to the corresponding annular space in the area of the guide gaps adjacent to the intake connection and, on the other hand, by other radial bores connected to the corresponding connection leading to the tank. In the neutral position of the multiway valve these two radial bores are open to the control chambers connected to the tank, while with the deflection of the piston slide valve from the center position into one or the other direction in each case a radial bore can be covered by the housing of the valve.
With this design of the multiway valve it is possible with the piston slide valve located in the blocking position to prevent effectively and with the least possible production and assembly expenditures overflow of the pressure medium from the intake chamber to the two actuator control chambers. Thus a particular advantage results from the fact that the housing of a conventional multiway valve can be used without any changes and only an exchange of the piston slide valve is needed to avoid an undesirable pressure buildup in the actuator connections.
However, limits of this usual multiway valve appear if there is a question of effectively excluding flow medium or pressure medium entries into the actuator connections if the tank itself is under pressure. Under these conditions, with known piston slide valves the pressure medium, due the fit clearance between piston slide valve and valve housing land, can reach the pressure medium in the adjacent operating pipe or actuator connection, which has an especially negative effect in the control of very sensitive actuators.